To preempt some of the traffic snarls at the sold out Legends of the Summer concert, Rose Bowl officials are asking people to show up several hours early and Metro is keeping most of its rail lines open late to accommodate the post-concert masses.

“This is a huge operation,” said Metro spokesman Jose Ubaldo. “I don’t think we’ve had a celebrity like Justin Timberlake and Jay-Z doing this together. So definitely it’s going to be huge.”

They’ve extended rail and bus hours after other concerts, too, Ubaldo said, and he urged everyone going to Sunday's concert to ditch their cars – and the headaches.

“You know it’s a great way for people to realize all the troubles they could avoid using transit,” he said. “They just get the ticket, get to the concert and go back home.”

As Rose Bowl employees braced for the powerhouse duo and their flock of fans, they encouraged people to show up early and have a picnic before the show. The on-site parking lots opened at noon – seven hours before the show starts.

The stadium’s Twitter account fielded scores of questions from people with last-minute parking qualms.

One person asked how much on-site parking would cost.

The stadium's account tweeted back: “It is $40 for general, $80 for preferred, and $160 for limo or bus.”

Another woman wondered if she'd have enough time to find parking if she arrived at 4 p.m.

The stadium's answer? Probably, but “the earlier the better.”

For a complete list of final train departure times after the show and information about the Rose Bowl's shuttle service, check Metro's posting about the concert.